ABSTRACT Purpose: To evaluate in-vivo degradation of two bioabsorbable interference screws. Methods: Twenty-two crossbred Santa Inês ewes were used. A poly-DL-lactide (PDLLA) screw (70%/30%) was inserted in the right pelvic limb, and a PDLLA screw (70%) + β-tri-calcium phosphate (β-TCP) (30%) in the left pelvic limb. Animals were euthanized at one, four, seven and a half and 18 months after surgery. Plain radiography, computed tomography (CT), microCT, and histological analysis were accomplished. Results: PDLLA screw was hypodense at all evaluation moments, but with progressive density increase along the central axis, whereas PDLLA/β-TCP was initially hyperdense and progressively lost this characteristic. No adverse reactions were observed on histological evaluation. Conclusions: The inclusion of β-TCP favors screw degradation since the PDLLA/β-TCP screws evidenced a more intense degradation process than the PDLLA screws at the last evaluation. PDLLA screws showed higher bone production, evident around the screw thread, inside the lateral perforations, and in the central canal, whereas the PDLLA/β-TCP screws presented less bone tissue at the implantation site.

OBJECTIVE: This study evaluated experimentally-induced periapical bone loss sites using digital radiographic and histopathologic parameters. MATERIAL AND METHODS: Twenty-seven Wistar rats were submitted to coronal opening of their mandibular right first molars. They were radiographed at 2, 15 and 30 days after the operative procedure by two digital radiographic storage phosphor plates (Digora®). The images were analyzed by creating a region of interest at the periapical region of each tooth (ImageJ) and registering the corresponding pixel values. After the sacrifice, the specimens were submitted to microscopic analysis in order to confirm the pulpal and periapical status of the tooth. RESULTS: There was significant statistically difference between the control and test sides in all the experimental periods regarding the pixel values (two-way ANOVA; p<0.05). CONCLUSIONS: The microscopic analysis proved that a periapical disease development occurred during the experimental periods with an evolution from pulpal necrosis to periapical bone resorption.

ABSTRACT OBJECTIVE: To analyze and to quantify morphological acinar postmortem changes in rat sublingual glands (SLG). MATERIAL AND METHODSs: Fifty rats were divided into two groups of 25 animals each. Group I was used for morphological and morphometric evaluations and group II for the determination of gland density and processed gland volume. Acinar autolytic changes were studied at 0 (control group), 3, 6, 12 and 24 h postmortem periods. The morphometric analysis of the volume density (Vv) and total volume (Vt) of intact (ia) and autolyzed (aa) acini was performed under light microscopy using a Zeiss II integration grid with 100 symmetrically distributed points. RESULTS: Morphologically, temporal progressive nuclear alterations and gradual loss of the structural architecture of acinar cells were found. Regarding quantitative results, both the Vvaa and the Vvia showed statistically significant differences among all postmortem periods (p<0.05). Vvaa increased from 0.42% at 0 h to 75.84% at 24 h postmortem and Vvia decreased from 71.16% to 0% over the same period. For Vtaa and Vtia, no statistically significant differences occurred between 12-24 h and 0-3 h (p>0.05), respectively. Vtaa increased from 0.18 mm³ at 0 h to 38.17 mm³ at 12 h, while Vtia showed a decrease from 33.47 mm³ to 0 mm³ between 3-24 h postmortem. Data concerning Vtaa were adjusted by two-variable linear regression, obtaining the equation: y=-3.54 + 3.38x (r²=0.90). The Vtaa growth rate calculated by this equation was 3.38 mm³/h between 0-12 h. CONCLUSION: Acinar autolysis on rat SLG demonstrated the most significant signs during the first 6 h postmortem and was widely spread through the gland at 12 h.

O objetivo deste estudo foi analisar morfometricamente a resposta tecidual a um pino obtido a partir de osso bovino desvitalizado cortical (DBCB pinos) implantado no tecido subcutâneo de ratos, bem como para avaliar o seu aspecto microestrutural por microscopia eletrônica de varredura (MEV). Os pinos foram implantados no tecido subcutâneo de 20 ratos, que foram sacrificados aos 7, 14, 28 e 60 dias (5 animais / período) após a implantação. No tecido subcutâneo, o pino DBCB promoveu a formação de uma cápsula fibrosa. Aos 7 dias, a cápsula apresentou espessura de 70 ± 3,2 μm com maior densidade de capilares neoformados e menor densidade de fibras colágenas. Entre 14 e 60 dias, a cápsula fibrosa apresentava-se mais organizada e exibiram menor espessura (53 ± 5,5 μm) com maior densidade de fibroblastos e fibras colágenas. Nesse período, foi observada uma bioreabsorção pequena e lenta dos pinos DBCB por macrófagos e raras células gigantes multinucleadas, sem dano tecidual. A espessura dos pinos DBCB reabsorvidos foi em média de apenas 9,3 µm. Durante todos os períodos experimentais não ocorreu presença de células como linfócitos e células plasmáticas. Concluiu-se que o pino derivado de osso bovino cortical foi bem tolerado pelo tecido subcutâneo de ratos e reabsorvido lentamente, sendo um potencial material alternativo para fixação da membrana nos procedimentos de regeneração tecidual guiada.

The aim of this study was to morphometrically analyze the tissue response to a customized pin obtained from devitalized bovine cortical bone (DBCB-pin) implanted in the subcutaneous tissue of rats, as well as to assess its microstructural aspect by scanning electron microscopy (SEM). The pins were implanted in the subcutaneous tissue of 20 rats, which were killed at 7, 14, 28 and 60 days (5 rats/period) after implantation. In the subcutaneous tissue, DBCB-pin promoted the formation of a fibrous capsule. At 7 days, capsule showed thickness of 70 ± 3.2 µm with higher density of newly formed capillaries and smaller density of collagen fibers. Between 14 and 60 days, more organized fibrous capsule exhibited smaller thickness (53 ± 5.5 µm) with higher density of fibroblasts and collagen fibers. In this period, a small and slow bioresorption of the DBCB-pin by macrophages and rare multinucleated giant cells without tissue damage was observed. The thickness of DBCB-pin resorbed was in mean only of 9.3 µm. During all experimental periods not occurred presence of immune reaction cells as lymphocytes and plasma cells. It was concluded that the pin derived from cortical bovine bone was well tolerated by subcutaneous tissue of rats and slowly resorbed could be an alternative material for membrane fixation in the guided tissue regeneration procedures.

Little information is available on the pathogenesis of fluorosis during the fetal and initial postnatal period. In the present study, female rats received 0 (control), 7 or 100 ppm of sodium fluoride in drinking water, one week before breeding and throughout gestation and nursing periods. The hemimandibles of the offspring were collected at 0, 7 and 14 days of postnatal life (n = 5) and processed for morphological analyses by light and electron microscopy, immunohistochemical analysis for amelogenin and morphometric study of enamel matrix and ameloblasts of incisors. The results showed a decrease in matrix production at the secretory phase at all study periods for the 100 ppm group. In this same group, the secretory ameloblasts showed reduction of enamel matrix secretion, disorganization of mitochondrial crests, large vacuoles at the apical portion of the cytoplasm, retention of intracisternal material and dilatation of some cisterns in the rough endoplasmic reticulum. In the groups of animals aged 7 and 14 days, analysis of variance showed significant reduction (p<0.05) in cytoplasmic volume of 23.80% and 24.75%, respectively, in relation to the control group. The smooth-ended maturation ameloblasts exhibited a large number of vacuoles with electron-dense endocytic matrix, suggesting a delay in the resorption process. Immunohistochemical analysis showed no difference in the intensity and labeling pattern of the enamel matrix in any study group. Interestingly, in offspring at the age of 14 days for the 7 ppm group, there was an increase in the matrix length at the secretory phase. Therefore, part of the excessive dose of sodium fluoride given to the mother in drinking water can reach the offspring through the placenta and mother's milk, causing morphological changes in ameloblasts and suggesting a reduction in secretion and a delay in matrix resorption.

Poucos estudos demonstram as reações patológicas devidas à inalação de fumaça pelas vias aéreas de ratos. OBJETIVO: Estudar e analisar os possíveis efeitos histopatologicos produzidos pela inalação crônica de fumaça de cigarro nas pregas vocais de ratos. DESENHO DE ESTUDO: Experimental. MATERIAL E MÉTODOS: 36 ratos masculinos (Rattus norvergicus Wistar), de 60 dias de idade, foram mantidos em gaiolas e expostos à inalação da fumaça produzida por 10 cigarros, 3 vezes ao dia, 7 dias por semana, para períodos de 25, 50 e 75 dias, e os controles respectivos. Os animais foram sacrificados e as suas laringes dissecadas e submetidas a análise histológica com coloração de Hematoxilina e Eosina e analisados através de microscopia simples. RESULTADOS: Os ratos expostos ao cigarro exibiram menor (p <0,05) massa corporal que o grupo controle. Havia hiperplasia e metaplasia escamosa na extremidade livre da prega vocal e hiperplasia escamosa na porção mediana da prega vocal em todos os 3 períodos de estudo. Além disso, o grupo de 50 dias revelou metaplasia com queratinização nesta área. Não foram observadas alterações morfológicas em outras áreas da laringe e reação inflamatória da lâmina propria. CONCLUSÃO: Foi concluído que a inalação passiva de fumaça de cigarro rende mudanças morfológicas importantes no epitélio da prega vocal que podem, eventualmente, progredir para neoplasia.

Few studies have demonstrated the pathologic reactions yielded by smoke inhalation on the airway in rats. AIM: The aim of this study was to analyze the possible histopathological effects produced by chronic cigarette smoke inhalation on the vocal folds of rats. STUDY DESIGN: Experimental. MATERIAL AND METHOD: 36 male rats (Rattus norvergicus Wistar strain), aged 60 days, were kept in cages and exposed to inhalation of the smoke produced by 10 cigarettes lit 3 times a day, 7 days a week, for periods of 25, 50 and 75 days, and their respective controls. Thereafter the animals were killed and their larynxes were dissected and submitted to histological processing for achievement of histological sections, which were stained with Hematoxylin and Eosin and analyzed by light microscopy. RESULTS: The rats exposed to smoke displayed smaller (p< 0,05) body mass than the control group. There was hyperplasia and squamous metaplasia in the free edge of the vocal fold and squamous hyperplasia on the middle portion of the vocal fold in all 3 study periods. Moreover, the 50-day group revealed keratinizing metaplasia in this area. Morphological alterations in other areas of the larynx and inflammatory reaction of the lamina propria were also not observed. CONCLUSION: It was concluded that the passive inhalation of cigarette smoke yields important morphological changes in the vocal fold epithelium, which may progress to neoplasia.

O crescimento das glândulas parótidas do camundongo durante 7 e 35 dias de vida pós-natal foi estudado por métodos morfométricos. A massa glandular, o volume de cada compartimento morfológico e o número de células em cada compartimento foram avaliados. Os dados obtidos para cada dimensão avaliada foram ajustados por equação exponencial, tipo Y = a.e k.x, permitindo o cálculo do seu tempo de duplicação médio (T D), ou seja, uma estimativa da sua velocidade de crescimento. A análise dos resultados mostrou a ocorrência de um marcante aumento de massa glandular no período estudado de 1.424%, com T D = 7,10 dias. Esse crescimento glandular ocorreu por aumentos nos volumes absolutos dos ácinos, dos ductos intercalares, dos ductos estriados, dos ductos excretores e do estroma, com aumentos percentuais de, respectivamente, 3.048%, 417%, 2.662%, 2.594% e 367%, e T Ds de 5,62, 11,71, 5,55, 5,47 e 14,45 dias. A análise da evolução do número de células em cada compartimento demonstrou aumentos de, respectivamente, 1.904%, 285%, 1.228%, 1.090% e 286% e T Ds de 6,62, 20,40, 7,19, 7,26 e 14,51 dias. Baseados nos resultados aqui obtidos, concluímos que o crescimento das glândulas parótidas do camundongo entre os dias 7 e 35 de idade ocorre por intenso acúmulo de células, principalmente nos ácinos e nos ductos estriados e excretores, com uma velocidade de crescimento sensivelmente maior que nos ductos intercalares e no estroma.

The growth of the mouse parotid glands during 7 and 35 days of postnatal life was studied by morphometric methods. The mass of the gland, the volume of each morphological compartment, and the cell number in each compartment were evaluated. The data obtained for each evaluated dimension were adjusted by an exponential equation, of the type Y = a.e k.x, thus permitting the calculation of their mean duplication time (T D), i.e., an estimation of their growth rate. Analysis of the results showed a marked 1,424% increase in the gland mass during the whole studied period, with T D = 7.10 days. This growth occurred by increases in absolute volume of acini, intercalated ducts, striated ducts, excretory ducts and stroma, with percentual increases of 3,048%, 417%, 2,662%, 2,594% and 367%, respectively, and T Ds of 5.62, 11.71, 5.55, 5.47 and 14.45 days, respectively. Analysis of the cell number growth in each compartment showed increases of 1,904%, 285%, 1,228%, 1,090% and 286%, respectively, and T Ds of 6.62, 20.40, 7.19, 7.26 and 14.51 days, respectively. Based on the present results, we concluded that the growth of the mouse parotid glands from day 7 to day 35 of age occurred by intense cell accumulation, mainly in the acini, striated ducts and excretory ducts, with a growth rate sensibly higher than that of the intercalated ducts and stroma.

O tecido ósseo possui grande potencial regenerativo com capacidade para restaurar completamente sua estrutura e função originais. Há situações em que os defeitos ósseos não conseguem por si só obter o reparo, casos em que se fazem necessários o uso de enxertos, para um correto tratamento e bom prognóstico. Este experimento teve o propósito de analisar microscopicamente o efeito do tamanho das partículas de matriz de osso medular bovino desmineralizado, nas formas micro e macrogranular, na reparação de defeito ósseo em fêmures de coelhos, tendo como controle o coágulo sanguíneo. Após 1,3 e 6 meses da implantação dos materiais, os animais foram mortos e as peças anatômicas removidas. Uma reação granulomatosa tipo corpo estranho, envolvendo as partículas implantadas, foi observada. Estes resultados sugerem falhas na desmineralização e/ou na retirada de potenciais antigênicos durante a produção do biomaterial. Podemos concluir que o tamanho das partículas não influenciou na evolução do processo reparativo dos defeitos ósseos, atuando apenas como substâncias osteopreenchedoras e que o material implantado deverá sofrer um aprimoramento no controle de qualidade na linha de produção, uma vez que poderá representar uma boa alternativa para enxertos ósseos.

The bone tissue has a great regenerative potential, with ability to completely restore its structure and original functions. In some situations, though, bone defects cannot be self-repaired, thus requiring the use of grafts for a correct treatment and good prognosis. This work aimed at microscopically analyzing the effect of the particle size of demineralized bovine cancellous bone matrix in micro and macrogranular forms on the repair of bone defects in femurs of rabbits, with blood clot used as control. At 1, 3 and 6 months after implantation of the materials, the animals were killed and the anatomic specimens were removed. A foreign body-type granulomatous reaction containing macrophages and multinucleated giant cells in contact with the implanted particles was observed. These results suggest a failure in demineralization and/or interruption of the antigenic potential during production of the biomaterial. It is concluded that the size of the particles did not influence the evolution of the repair process of bone defects, acting only as bone-filler substances, and that the material implanted should be improved by quality control during production, since it may represent a good alternative for bone graft.

A capacidade de um pool de proteínas morfogenéticas bovinas ligada a hidroxiapatita sintética absorvível microgranular (BMPb-HA) em estimular a reparação óssea foi avaliada em defeito de tamanho crítico em calvária de rato. Defeitos de 8 mm diâmetro foi produzido na calvária de 25 ratos, sendo 15 preenchidos com BMPb-HA homogeinizado com sangue (grupo experimental) e 10 somente com coágulo sanguíneo (grupo controle). As calvárias dos animais do grupo experimental foram coletadas 1, 3 e 6 meses após as cirurgias e as do grupo controle, ao término da cirurgia e após 6 meses. Os resultados morfométricos obtidos nas imagens radiográficas apresentou ausência de formação óssea nos períodos de 1 e 3 meses e, histologicamente os defeitos estavam preenchidos por tecido conjuntivo fibroso e inúmeros focos de reação granulomatosa, tipo corpo estranho, ao redor de aglomerados de hidroxiapatita. Ao final de 6 meses, os focos de reação granulomatosa diminuiu em número e tamanho e os defeitos diminuíram a sua área em 22% em relação ao controle 0 hora, devido a neoformação óssea nas suas bordas, mas apresentaram área semelhante ao controle 6 meses. Concluímos que a utilização de BMPb-HA no tratamento de defeitos ósseos cranianos em ratos, promove a formação de reação granulomatosa tipo corpo estranho que inibe profundamente a neoformação óssea, sugerindo que a hidroxiapatita sintética microgranular não é um bom carreador para as BMPs expressarem o seu potencial indutor.

The ability of a pool of bovine bone morphogenetic proteins bound to synthetic microgranular hydroxyapatite (BMPb-HA) to stimulate bone repair was determined in rat critical size defects. An 8-mm diameter defect was created in the calvaria of 25 rats. In 15 rats, the defects were filled with BMPb-HA homogenized with blood (experimental group), and in 10 rats the defects were filled only with blood clots (control). The calvariae of experimental rats were collected 1, 3 and 6 months after surgery and of the control rats at the end of surgery and 6 months thereafter. The morphometric results obtained in the radiographs showed an absence of new bone formation at 1 and 3 months post-surgery and, histologically, the defects were filled with fibrous connective tissue and numerous foci of a foreign body-type granulomatous reaction around hydroxyapatite agglomerates. At the end of 6 months, the number and size of the granulomatous foci decreased and the area of the defects was reduced by 22% compared to the 0-hour control due to the formation of new bone at their borders, although the mean area was similar to the 6-month control. We conclude that the use of BMPb-HA in the treatment of critical size bone defects of the rat skull leads to the formation of a foreign body-type granulomatous reaction that markedly inhibits new bone formation, suggesting that synthetic microgranular hydroxyapatite does not represent a good carrier for BMP-induced bone formation.

A ocorrência de diferenças morfológicas entre sexos na glândula sublingual de ratos adultos foi verificada pela morfometria. As massas glandular absoluta e relativa das fêmeas foi, respectivamente, 21% menor e 31% maior que as dos machos. As frações de volume glandular ocupadas pelos ácinos mistos, ductos intercalares e ductos estriados não mostraram diferenças significantes entre sexos, no entanto, os seus volumes absolutos foram, respectivamente, 29%, 42% e 58% maiores nos machos. Apesar dessas diferenças nos volumes compartimentais, os seus conteúdos em número de células não apresentaram diferenças significantes entre sexos, exceto o compartimento dos ductos excretores, que mostrou maior número nos machos. Quanto ao volume celular, as células acinosas mucosas, as dos ductos estriados e as dos ductos excretores mostraram volumes, respectivamente, 13%, 33% e 47% maiores nos machos, e o das células das semiluas serosas foi 38% maior nas fêmeas. A relação superfície-volume dos ácinos e dos ductos estriados foi, respectivamente, 16% e 35% maior nas fêmeas. Baseados nos resultados obtidos, concluímos que as glândulas sublinguais das fêmeas exibem ácinos menores e ductos mais curtos e menos calibrosos e células acinosas mucosas menores e serosas maiores do que nos machos, indicando a ocorrência de dimorfismo sexual, e sugerindo que possa haver também diferenças na qualidade do produto secretado.

The presence of morphological differences in the sublingual gland of male and female adult rats was determined by morphometry. Absolute and relative glandular mass was 21% lower and 31% higher, respectively, in females than in males. The fractions of glandular volume occupied by the mixed acini, intercalated ducts and striated ducts did not differ significantly between genders; however, their absolute volume was respectively 29, 42 and 58% higher in males. Despite the differences in the volume of these morphological compartments, the number of cells did not differ significantly between genders, except for the excretory duct compartment, for which a larger number was observed in males. With respect to cell volume, 13, 33 and 47% higher volumes were observed in males for mucous acinar cells and striated and excretory duct cells, respectively, while a 38% higher volume of serous demilune cells was observed for females. The surface-to-volume ratio of acini and striated ducts was respectively 16 and 35% higher in females. Based on these results, we conclude that the sublingual gland of female rats possesses smaller acini, and shorter ducts whose caliber is narrower, smaller mucous acinar and larger serous cells than the ones found in the male gland, indicating the presence of sexual dimorphism as well as suggesting sexual differences in the quality of the secreted product.

Nos últimos anos, vários materiais de origem bovina para enxerto ósseo têm sido lançados no comércio para serem utilizados em cirurgias bucomaxilofaciais. Na presente pesquisa avaliamos a capacidade de um material de enxerto ósseo orgânico em bloco (Gen-ox, Baumer SA - Brasil) preparado à partir de osso medular bovino, em promover a reparação de lesões ósseas de tamanho crítico em calvária de ratos. Uma lesão trans-óssea de aproximadamente 8mm de diâmetro foi realizada com trefina cirúrgica nos ossos parietais de 25 ratos, sendo que em 15 os defeitos foram preenchidos com bloco de 8mm de diâmetro do material de enxerto, embebida com sangue do próprio animal e em 10 somente com coágulo sanguíneo. As calvárias dos ratos tratados com o material foram coletadas após 1, 3 e 6 meses após as cirurgias e dos tratados com coágulo sanguíneo, imediatamente após as cirurgias e decorridos 6 meses. Durante as cirurgias verificamos que esse material enxertado é de fácil manuseio e se adapta perfeitamente ao leito receptor após sua embebição com sangue. Os resultados obtidos mostraram que na maioria dos casos tratados, o material foi reabsorvido lentamente e serviu como material de preenchimento e mantenedora de espaço, favorecendo a angiogênese, migração e adesão celular e a neoformação óssea à partir das bordas da lesão. No entanto, em 2 casos no subgrupo tratado - 1 mês e 1 caso no subgrupo tratado - 3 meses, ocorreu a presença de reação granulomatosa tipo corpo estranho com a presença de inúmeras células gigantes, que inibiu a neoformação óssea local. Esses casos foram interpretados como decorrentes de falhas na desmineralização e na retirada de potenciais fatores antigênicos durante a produção do biomaterial. Concluímos que com um aprimoramento do controle de qualidade na linha de produção do material, a matriz orgânica medular em bloco poderá ser uma boa alternativa para ser usada no reparo de defeitos ósseos na região buco-maxilofacial, devido a sua alta capacidade osteocondutora.

Over the last few years, various bone graft materials of bovine origin to be used in oromaxillofacial surgeries have entered the market. In the present study, we determined the capacity of a block organic bone graft material (Gen-ox, Baumer SA, Brazil) prepared from bovine cancellous bone to promote the repair of critical size bone injuries in rat calvaria. A transosseous defect measuring approximately 8mm in diameter was performed with a surgical trephine in the parietal bone of 25 rats. In 15 animals, the defects were filled with a block of graft material measuring 8mm in diameter and soaked in the animal's own blood, and in the other 10 animals the defects were only filled with blood clots. The calvariae of rats receiving the material were collected 1, 3 and 6 months after surgery, and those of animals receiving the blood clots were collected immediately and 6 months after surgery. During surgery, the graft material was found to be of easy handling and to adapt perfectly to the receptor bed after soaking in blood. The results showed that, in most animals treated, the material was slowly resorbed and served as a space filling and maintenance material, favoring angiogenesis, cell migration and adhesion, and bone neoformation from the borders of the lesion. However, a foreign body-type granulomatous reaction, with the presence of numerous giant cells preventing local bone neoformation, was observed in two animals of the 1-month subgroup and in one animal of the 3-month subgroup. These cases were interpreted as resulting from the absence of demineralization and the lack of removal of potential antigen factors during production of the biomaterial. We conclude that, with improvement in the quality control of the material production, block organic bone matrix will become a good alternative for bone defect repair in the oromaxillofacial region due to its high osteoconductive capacity.

Ameloblastos são células de origem epitelial, que apresentam funções de síntese, secreção e maturação do esmalte dental. Assim sendo, ameloblastos passam por mudanças morfológicas durante o seu curso de desenvolvimento. Desse modo, cinco ratos adultos Wistar foram utilizados para avaliar a morfologia de ameloblastos da fase secretora e em maturação, usando de métodos estereológicos em microscopia eletrônica de transmissão. Os dados foram analisados pela análise de variância a um critério (ANOVA). Os resultados mostraram que da fase de secreção para a de maturação da amelogênese: a) ocorreu uma redução de 23% no volume absoluto nuclear e o volume absoluto citoplasmático não mostrou diferença estatisticamente significante (p>0.05); b) o volume total e a superfície total do retículo endoplasmático rugoso (RER) diminuíram 74% e 90%, respectivamente; c) o volume total e a superfície total das mitocôndrias aumentaram 742% e 384%, respectivamente; d) a relação superfície-volume do RER e das mitocôndrias diminuíram 59% e 42%, respectivamente; e) os pequenos grânulos de secreção, dispostos principalmente na área apical, desapareceram junto com o Processo de Tomes e apareceram os lisossomos e vacúolos digestivos principalmente na área supranuclear. Portanto, apesar de ocorrer uma significante adaptação morfológica durante a modulação da fase secretora para a de maturação do desenvolvimento do esmalte, o volume citoplasmático do ameloblasto permanece inalterado.

The ameloblasts both in secretion phase and in smooth-ended ameloblasts in maturation phase were studied using stereologic methods in transmission electron microscopy (TEM). From secretion to maturation phase of amelogenesis, the nucleus volume decreased 23% and cytoplasm volume did not show significant changes; the total volume and surface of the rough endoplasmic reticulum (RER) decreased 74% and 90%, respectively, and of the mitochondria increased 742% and 384%, respectively; the surface-to-volume ratio for RER and mitochondria decrease 59% and 42%, respectively; and the predominantly apical secretory granules disappeared joined at Tomes’ process and lysosomes and phagic vacuoles have appeared principly in supranuclear cytoplasm. Although significant morphologic variation occurs from the secretory to the maturation phase of the ameloblasts, their cytoplasm volume remains unaltered.